A new diagnosis of congestive heart failure (CHF) is made in 400,000 Americans each year. Those with moderate left ventricular dysfunction have a substantial risk of premature death, approximately 25% over 2-1/2 years. Between 30% and 50% of these deaths are thought to be sudden, due to arrhythmias, and may be preventable. CHF patients represent the largest single identifiable population of patients that can be targeted for prevention of sudden cardiac death (SCD).